def build_person(first_name,last_name):
    '''Return a dictionary containing information about a person'''
    person={'first':first_name,'last':last_name}
    return person

musician=build_person('jimi','hendrix')
print(musician)

def build_person(first_name,last_name,age=None):
    '''Return a dictionary containing information about a person'''
    person={'first':first_name,'last_name':last_name}
    if age:
        person['age']=age
    return person

musician=build_person('jimi','hendrix',27)
print(musician)